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So I needed to change the air filter on my '72 Supreme and I had two spares in the garage. One being the standard STP, and the other being a Napa Pro Select #22095. The one I had on the car was a WIX #42095.
When I compared the 3, I noticed that the pleating and the wire mesh were different.
Here's the WIX
The Napa
...and the STP
Notice that the pleating on the WIX is closer together than the Napa and the STP. Also notice that the mesh on the STP is more "open." Would this indicate that the WIX would be the better of the 3 since the pleats are closer together? For now I used the NAPA since it seemed to me to be the better choice over the STP.
I think you would be good with the NAPA filter. Some (maybe all) of the NAPA filters are made by Wix. Wix is always the best. I would throw the STP filter in the trash.
I remember reading somewhere that Wix is no longer the supplier for NAPA so you may want to stick with Wix.
That said, it's an air filter. I don't think it makes all that much difference as long as it's clean. Actually, the Wix that you're replacing looked fine to me. I tend to save my episodes of OCD for oil filters.
I remember reading somewhere that Wix is no longer the supplier for NAPA so you may want to stick with Wix.
That said, it's an air filter. I don't think it makes all that much difference as long as it's clean. Actually, the Wix that you're replacing looked fine to me. I tend to save my episodes of OCD for oil filters.
Well, according to my records, I last changed my air filter 16,000 miles ago back in Apr 2019, so I felt it was time...it looked dirty.
Before the tomahawks fly, consider how filtration works...
The dirt gets stopped when it encounters a hole that is smaller than the dirt particle.
There is still a bit of space between the dirt and the hole, so some air continues to flow in that location.
That bit of space is smaller than the original hole, so it filters out smaller particles than the original hole could.
The reason we change filters is that as they fill up, the pressure drop increases and flow drops. As well, a plugged filter can collapse due to pressure difference, releasing much of its trapped dirt.
For an automotive air filter, plugging leads to power loss (from lower air flow).
The ideal filter is one that has both high flow and fine particle filtration. And there are sites that publish tests for these parameters.
Not saying "buy Wix" is not a good suggestion. I'm explaining this because I know you appreciate having a good understanding of what goes on in your car.
In terms of filtering surface area alone, the Wix appears to be the largest, the NAPA the smallest, and the STP somewhere in between. Wouldn't the time it takes to begin restricting flow be proportional to the filter area (all else being equal)?
Paper air filters work by trapping dirt particles in the paper. As the paper fills up with particles, the airflow restriction increases. This causes loss of power and rich mixture in an open-loop carbureted engine. More filter media area prolongs the time until the filter needs to be replaced and reduces restriction while it's in use. The filter with tighter filter media pleats (as in, the Wix) has more filter media area and is the better filter to use. Less filter media (wider pleats) means lower production costs at the expense of performance. And this assumes the same quality filter media, of course.
Paper air filters work by trapping dirt particles in the paper. As the paper fills up with particles, the airflow restriction increases. This causes loss of power and rich mixture in an open-loop carbureted engine. More filter media area prolongs the time until the filter needs to be replaced and reduces restriction while it's in use. The filter with tighter filter media pleats (as in, the Wix) has more filter media area and is the better filter to use. Less filter media (wider pleats) means lower production costs at the expense of performance. And this assumes the same quality filter media, of course.
And this is why I took a quick trip to the local auto parts store and picked up another Wix and put that one on instead of using the Napa.
Seems you're over analyzing a bit. Why go spend money on more filters when you have several sitting on a shelf? Just use them up and change when they get dirty. I really don't think you'll see a difference in performance in any of them.
